Process for the production of ferromanganese



65 weakly acid nature that a splitting-up of the Patented Aug. 30,

UNITED STATES I PATENT OFFICE 2,128,615 Process non. 'rns PRODUCTION ormano- MANGANESE No Drawing. Application June 13, 1935, Serial No.26,514. In Germany July 23, 1934 3 Claims.

In the manufacture of term-manganese in the blast furnace, that is tosay by the manufacturing process which has been hitherto usual, it isnecessary, in view of the nature of the process, to select oresthe'manganese content of which is in I a quite definite proportion tothe iron content. Thus, for example, 80% term-manganese can beobtainedby blowing in the blast furnace only if r a manganese ore beemployed the manganese content of which is at least 40% and the ironcontent whereof is at the most 4%. Ores having a lower manganesecontent, for example ores containing 43% iron and 8.5% manganese,produce when blown in the blast furnace a pig iron containing 11.5%manganese at the most. Apart from this necessity of selecting ores whichcontain a definite proportion of iron relatively to manganese, theprocess of manufacturing ferromanganese in the blast furnace is alsoexpensive due to the high consumption of fuel and the considerable wearand tear on the blast furnace.

The subject matter of the present invention is a process for themanufacture of ferro-manganese from manganese ores or manganese slagswhich, owing to the proportion of iron to manganese which they contain,cannot be worked up to ferro-manganese in one working stage. Inaccordance with the new process these ores or slags are worked up in anopen hearth or rotary furnace to produce a low-melting manganous oxideslag. In this operation so much of the ironfrom them and the slag isreduced that an intermediate product is obtained having the properproportion of iron to manganese for producing the ferro-manganesedesired. v This intermediate product is then worked up in the usualmanner to produce ferro-manganese. The entire process proceeds by way ofthe liquid phase so that it can be carried out in a particularly simplemanner and the separation of iron and manganesecan conveniently beregulated in such a manner that an intermediate product is formed inwhich the ratio of iron to manganese is as desired for the finalproduct. I

With this separation of iron and manganese by way of the liquid phase,which-alone produces a useful method for the manufacture offerromanganese, certain precautions should be. taken when carrying outtheprocess. Thus, in order to effect the reduction of the iron but notthat of the manganese the charge should be mixed, in accordance with theinvention, in such a manner that there is formed in the first place alow melting manganous oxide slag of such a neutral or manganese oxidedoes not occur at the temperature necessary for the reduction of theiron.

It will be understood that in defining the nature of the slag as to itsbasic, neutral or acid nature,

the effect of the manganous oxide is not con-- sidered. In other words,while manganousoxide is sometimes elsewhere considered to be a base, itis not to be so considered for the purpose of the present specificationand invention.

In the first stage of the process, that is to say during the manganeseenrichment, therefore, an easily fusible slag which at the most may beneutral but is preferably slightly acid is aimed at and is worked attemperatures lying below the reduction temperature of the manganousoxide. In the second stage of the process, 1. e. on the reduction of themanganese and of the iron to ferro-manganese, the temperature of thefurnace is increased and so much lime is added to the product of thefirst stage, that is to say to the enriched manganous oxide slag, thatit .becomes highly basic, or alkaline.

The first stage of the new process is preferably carried out in' a drumor rotary furnace. An open hearth furnace can, of course, also be usedfor this purpose. The iron, which is reduced from the manganous oxideslag at a temperature below the reduction temperature of the manganesecan be continuously or intermittently removed from the furnace. The twostages of the process, that is to say the manganese enrichment stage andthe'reduction to ferro-manganese, can be carried out one after the otherin the same furnace. The manufacture of the ferro-manganese from theintermediate product may also be-effected, however, in a second furnace.

The new process for the manufacture of ferromanganese, as will be clear;without further explanation, is simple to carry out and is considerablymore adaptable than the known blast furnace process and the other method.of manufacture hitherto known. The fractional reduction by way of theliquid phase affords a certain procedure which can be easily carried outin practice We claim:

1. Process for the manufacture of ferro-manganese from iron-containingmanganese ores or manganese slags which. owing to the proportion of ironto manganese which they contain, cannot be worked upto term-manganese;in a single working process wherein 'the ore, after being mixed withlimestone, is melted to form a lowmelting manganous oxide slag ofneutral or weakly acid reaction, and so much iron is reduced out of theslag at a temperature below the reduction temperature of the manganeseas to form an intermediate product in which the proportion of iron tomanganese is that required for producing the term-manganese desired, andthe intermediate product is then reduced to fern-manganese in the usualmanner.

2. Process for the manufacture of ierro-manganese from iron-containingmanganese ores or manganese slags which, owing to the proportion of ironto manganese which they contain, cannot be worked up to term-manganesein a single working process, wherein the ore, after being mixed withlimestone and fluorspar, is melted to form a low-melting manganous oxideslag of neutral or weakly acid reaction, and so much iron 5 is reducedout of the slag at a temperature below ADOLF KRUS. HERMANN S'I'EFFE.

